The purpose of the work described in this proposal is to continue study of the mechanism of cellular immunity and hypersensitivity. Our aim is to acquire knowledge of basic mechanisms which can be used to rationally manipulate these cellular processes in certain human clinical conditions where enhancement of cellular immunity might lead to prevention or alleviation of disease such as infections or neoplasia, or where suppression might diminish tissue injury caused by cellular hypersensitivity. The proposed investigation is a direct outgrowth of our interests in the interaction of lymphocytes, their mediators and macrophages in cellular immunity. Studies on this project will include further characterization of the macrophage glycolipid which appears to act as a receptor for the lymphocyte mediator, MIF; further characterization and purification of MIF, and continued studies on MIF-macrophage interactions. Further studies on the mechanism of macrophage activation will be carried out. The glycolipid and glycoproteins of macrophage membranes obtained from control and activated macrophages will be analyzed. The mechanism of collagen-induced arthritis in the rat which we have shown to be mediated by cells will be further studied, focussing on immunologic ways to suppress it.